Optical devices that utilize a fluid (usually within or in contact with a membrane) to adjust or change the optical properties of a lens are known. These devices typically alter the volume or pressure of the fluid to cause the membrane to change its curvature, thus creating an optical interface with greater or less refractive power at that interface. In these devices, an increase in volume of a fluid contributes to an increase of positive (plus) optical power, and a decrease in volume of the fluid contributes to a reduction of positive (pus) optical power and/or increase of minus (negative) optical power.
However, such fluid lenses often have drawbacks that make them less than ideal, particularly for use in daily applications such in eyeglasses, contact lenses, spectacles, or other ophthalmic devices. For instance, these types of fluid lenses typically require a large volume of fluid to effectively increase the optical power to desired levels over a sufficient optical area, making it difficult to include such lenses in ophthalmic devices and in other optical applications. Also, due in part because of the large amount of fluid that may be required, it may take a relatively long amount of time to alter the focus of the fluid lens to a desired amount of optical power because this volume of fluid must be displaced.
In addition, these types of fluid lenses typically have a limited ability to be customized for astigmatic correction for the wide variety of eyeglass or optical prescriptions of wearers or users, and also provide manufacturers with a limited ability to edge and/or shape the fluid lens into the wide variety of shapes and sizes of the various eyeglass fashions available to be worn by a wearer or user. Furthermore, these types of fluid lenses generally have a very limited ability to decenter for the wearer or user's inter papillary distance needed and/or for the fitting height needed. In addition, these fluid lenses provide a limited ability for established wholesale laboratories to process the lenses using their present equipment into the lenses of the correct prescription, shape; size and alignment for the wearer's visual needs and/or requirements.
Moreover, as noted above, the adjustment of the optical power is typically achieved by a change in shape of a membrane, which is difficult to control and maintain, and in some cases (such as when creating parabolic or cylinder shapes) it is extremely difficult to achieve the level of precision desired. Many of these fluid lens have no real safeguard so as to guarantee that it will repeatedly switch to the required optical power for a wearer, meaning that the fluid lens can often over shoot or undershoot the required optical power. If left to the wearer to determine this optical power simply by looking through the fluid lens for clarity, it may also be that case that the wearer will prefer more optical plus or minus optical power than required and therefore over time weaken his or her eyes.